Non-volatile memory (NVM) circuits, such as electrically erasable programmable read-only memory (EEPROM) circuits have achieved widespread adoptions for code and data storage applications. An important aspect of NVM circuits is their performance, which includes endurance (number of programming or write/erase cycles) and data retention after write/erase cycling. Within the industry, the performance of NVM technology has been characterized extensively. Generally, the NVM circuits should be able to endure over 100 thousand to 1 million programming cycles with data retention exceeding 20 years, even at extreme ambient temperatures.
Memory operations, such as programming and erasing, may involve, for example, charging or discharging electrons from a floating gate of a NVM cell. The charging and discharging of electrons may be achieved by hot carrier injection (HCI) or Fowler-Nordheim (FN) tunneling. High voltages are used to perform certain memory operations. However, high voltages can cause junction breakdown or degradation.
It is desirable to provide memory cells with improved reliability even when exposed to high voltages.